Clustering states in the62Ni(58Ni,58Ni)62Ni reaction

Excitation function and angular distributions of the⁶²Ni(⁵⁸Ni,⁵⁸Ni)⁶²Ni elastic scattering have been measured at incident⁵⁸Ni energies from 220.0 to 230.0 MeV in steps of 0.5 MeV. Evidence of two structures was found in the excitation function; a statistical analysis suggests a possible nuclear cluster quasi-molecular nature for these structures.     

Evidence of non-statistical structures in the elastic and inelastic scattering of58Ni+58Ni and58Ni+62Ni and intermediate dinuclear states

Excitation functions and angular distributions of⁵⁸Ni+⁵⁸Ni and⁵⁸Ni+⁶²Ni scattering at energies just above the Coulomb barrier have been measured aroundθ _cm=90° in energy stepsΔE _cm=0.25 MeV fromE _cm ? 110 MeV toE _cm ? 120 MeV for⁵⁸Ni+⁵⁸Ni and fromE _cm ? 110 MeV toE _cm ? 118 MeV for⁵⁸Ni+⁶²Ni. Evidence for structure of non-statistical character has been found in the angle-summed excitation functions; this evidence is corroborated by the analysis of the angular distributions. This is the first time that non-statistical structure in elastic and inelastic scattering is reported with high confidence level for this mass and excitation energy ranges. Attempts are presented to understand the nature of this structure, including the presence of intermediate dinuclear states and virtual states in a potential well.     

Sub-barrier fusion of35, 37Cl+58, 64Ni evidence of effects of proton transfer channels

Sub-barrier fusion excitation functions of^35,37Cl+^58,64Ni have been measured. They are discussed in comparison to similar data of^34,36S+^58,64Ni with the aim of revealing the influence of coupled proton transfer channels. Using the simplified coupled channel code CCFUS, differences in the effects of inelastic channels are eliminated in an approximative manner to stress the differences in the effects of transfer channels. Signatures of positiveQ-value transfer channels coupled to fusion are clearly identified.     

Nuclear quadrupole-quadrupole interaction in the inelastic scattering of aligned deuterons from deformed nuclei

The 2 ₁ ⁺ -excitation of deformed nuclei by tensor polarized deuterons provides an alignment of both nuclei and thus a means to study specifically the quadrupole-quadrupole interaction between both nuclei. The tensor analyzing powerA _xz (θ) has been measured for the elastic and inelastic scattering on²⁴Mg and²⁸Si. The coupled channel analysis including a deformed tensor potential reveals a clear signature of the quadrupole-quadrupole part of the nuclear projectile-target interaction.     

The interaction between positive pions and deuterons at 47.5 MeV

The interaction of 47.5 (±0.5) MeV positive pions with douterons was studied using a scintillation counter telescope as the pion spectrograph. With an energy resolution sufficient to separate the elastic from inelastically scattered pions, the system was used to measure the cross sections for these reactions as well as the non-radiative pion capture process over the angular range of 22.5°–157.5°. The scattering results are well-fitted by recent theoretical calculations provided appropriate pion-nucleon phase shifts are used. The protons from the non-radiative capture reaction are fitted by a differential cross section of the form: $\text{d}\text{σ/}\text{d}\text{Ω ∝ A +}\text{cos}{}^2\text{θ}$, with A = 0.31 ± 0.03.     

Damped oscillations in the energy autocorrelation functions of the 58Ni+46Ti elastic and 58Ni+62Ni elastic and inelastic scattering cross sections

Structures of non-statistical character, recently observed in ⁵⁸ Ni +⁴⁶ Ti elastic and ⁵⁸ Ni +⁶² Ni elastic and inelastic excitation functions, produce damped oscillations in the cross section energy autocorrelation functions. The analysis of these damped oscillations in terms of S-matrix spin and parity decoherence indicates, as a possible interpretation, damping of the coherent rotational motion of the intermediate dinuclear system formed in the reaction.     

The interaction of aligned 7Li with 58Ni

Elastic and inelastic scattering of aligned ⁷Li on ⁵⁸Ni was studied experimentally for several energies between 14 and 22 MeV. Complete sets of second-rank tensor analyzing powers were measured for two energies, 14.2 and 22.0 MeV. The shape-effect model has been used for a qualitative interpretation of the data. The success of this model indicates the spectroscopic deformation of ⁷Li to be the main source of the observed second-rank tensor analyzing powers. The result enters the formulation of the diffraction as well as the optical model both of which are used to improve the analysis of the data. Besides the parameters which determine the central interaction the spectroscopic deformation was the only adjustable parameter. The deformation was found to be negative, in agreement with the oblate shape of ⁷Li. However the extracted value of the deformation varies within a factor of two when comparing different experiments and/or analyses with different models. The second-rank tensor analyzing powers for projectile excitation are roughly explained by the assumption that the angular momentum transfer is perpendicular to the momentum transfer.     

Elastic scattering of polarized deuterons from Al, Si and Ni between 7 and 11 MeV

Polarization parameters have been determined for deuteron elastic scattering from ²⁷Al, Si and ⁶⁰Ni at energies between 7 and 11 MeV and laboratory scattering angles from 30° to 135°. The vector polarization, iT₁₁, and two tensor parameters T₂₀ and T₂₂, were measured by scattering polarized and unpolarized deuterons which were obtained from a tandem accelerator. The largest polarization was |iT₁₁| ≈ 0.3 and |T₂₀| ≈ 0.2 for ²⁷Al at 11 MeV. For ⁶⁰Ni, the observed polarizations were substantially smaller. Angular distributions of the unpolarized cross section were also measured for ²⁷Al and Si. An optical-model analysis of the polarization and cross-section data was performed. The vector polarization was reproduced reasonably well by a vector spin-orbit coupling of similar strength as found for nucleon scattering. A tensor interaction appears to be needed to account for the observed tensor polarizations.     

Fusion excitation function measurements for the 16O+58Ni and 16O+62Ni systems

High precision fusion excitation functions have been measured for the ¹⁶O+⁵⁸Ni and ¹⁶O+⁶²Ni systems from which fusion barrier distributions have been evaluated. Coupled-reaction-channels (CRC) calculations, which describe elastic and quasi-elastic scattering, also satisfactorily reproduce the fusion cross sections and barrier distributions. The small value of Z₁Z₂ in this case leads to barrier distributions with relatively little structure. However, in conjunction with the detailed elastic scattering data for these systems, this allows us to elucidate the role of previously ignored states in ¹⁶O in pushing the entire distribution to lower energies. These shifts are consistent with derived magnitudes of polarization potentials for both systems.     

Elastic interaction between small nuclei

The radial distribution of gold nuclei obtained by evaporation in UHV onto alkali halide surfaces is measured, and is analysed in terms of parameters such as the nature of the substrate and the mean diameter of nuclei. This analysis seems to prove the presence of repulsive elastic forces between nucleus pairs due to the overlap of the strain fields induced by the nuclei in the substrate.     

Potential of interaction between nuclei and nucleon-density distribution in nuclei

Nuclear-interaction potentials that are calculated by using Skyrme forces within the extended Thomas-Fermi approximation and Hartree-Fock-Bardeen-Cooper-Schrieffer theory are studied in detail. It is shown that the nuclear component of the potential simulating the interaction between nuclei grows with increasing number of neutrons in colliding isotopes and with increasing diffuseness parameter of the density distribution in interacting nuclei. An increase in the diffuseness parameter of the density distribution in interacting nuclei leads to a decrease in the height of the barrier between the nuclei and to an increase in the depth of the capture well and in the fusion cross section. It is shown that the diffuseness parameter calculated for the nuclear component of the potential at large distance between interacting nuclei by using Skyrme forces exceeds the diffuseness parameter of the nucleon-density distribution in these nuclei by a factor of about 1.5. Realistic values of the diffuseness parameter of nuclear interaction between medium-mass and heavy nuclei fall within the range a ≈ 0.75–0.90 fm.     

Study on the probability of interaction between the plasmons of metal and deuterons

Summary In this work we have studied the influence of the impurity concentration on the phenomenon of fusing of deuterons, catalyzed by the ?efficacious? interaction with the plasmons of the metal. The numeric calculation, conducted on different metals considering the degree of impurities present in the reticulum, shows that the probability of fusion is amplified by the impurities. This result is confirmed qualitatively by the trend of the potential gap that describes the interaction inside the metal.     

Elastic scattering of35Cl from27Al,58, 62Ni,116, 120, 124Sn and141Pr

Elastic scattering angular distributions for³⁵Cl from²⁷Al,^{58, 62}Ni,^{116, 120, 124}Sn and¹⁴¹Pr have been measured at energies between 100 and 170 MeV. Optical model analyses have been performed to determine reaction cross sections, strong absorption radii and grazing angular momenta. The results are compared with the corresponding quantities extracted by means of the Fresnel scattering model. Near the interaction barrier the quarter point method yields reaction cross sections systematically smaller than the optical model results. The interaction radii, however, do not show significant differences or energy dependencies. These radii are compared with trend formulae for interaction radii, and comparisons with fusion radii are made.     

Study of the spectra of fast deuterons produced in the interaction of 670 MeV protons with nuclei

The spectra of deuterons emitted at angles of 6.5°, 9.5°, 13.5° and 16° (lab system) in the interaction of protons with the nuclei ¹H, ²H, ⁶Li, ⁷Li, C, Al, Cu, Rh and Pb have been measured in the momentum range 700–1700 MeV/c. The secondary particles were analyzed with the help of magnetic and time-of-flight spectrometers. The differential cross sections for deuteron production in the reactions p + 〈2N〉 → N + d and p + 〈N〉 → d + π have been measured for selected nuclei and angles. The effective numbers of nucleons and of two-nucleon clusters for the investigated nuclei were determined. The results obtained are discussed in terms of the dispersion theory of direct nuclear reactions.     

Measuring elastically scattered 18 MeV deuterons and the shape of nuclei

The angular distributions of 18 MeV deuterons elastically scattered on ⁹Be, ¹⁰B, ¹³C, ²⁴Mg, and ²⁵Mg nuclei are measured using the U-150M cyclotron at the Institute for Nuclear Physics (Almaty, Kazakhstan). The free parameters of the scattering matrix of parametrized phase analysis are determined. We estimate the sign of the nucleus??s deformation for even nuclei ⁶⁴Ni, ⁶⁴Zn, ¹⁴⁴Sm, ¹⁸²W, ¹⁸⁴W, ¹⁹²Os, ²³⁸U, and odd nuclei ⁵⁹Co, ⁶³Cu, ⁸⁹Y, ⁹³Nb, ¹⁰³Rh, ¹⁰⁷Ag, ¹⁸¹Ta, ¹⁹⁷Au, ²⁰⁵Tl, and ²⁰⁹Bi.     

Production of proton-rich actinide nuclei in the multinucleon transfer reaction 58Ni+232Th

In recent years,multinucleon transfer reactions have attracted significant attention for their potential to synthesize new exotic nuclei.These nuclei are difficult to be produced in fusion-evaporation reactions and fragmentation processes due to the extremely small production cross sections and/or the lack of appropriate projectile-target combinations.In the early 1970s,multinucleon transfer reactions have been used for the production of the light neutron-rich isotopes [1].     

Decay of proton-rich nuclei between 39Ti and 49Ni

Decay studies of very neutron-deficient nuclei ranging from ³⁹Ti to ⁴⁹Ni have been performed during a projectile fragmentation experiment at the GANIL/LISE3 separator. For all nuclei studied in this work, ^{39, 40}Ti, ^{42, 43}Cr, ⁴⁶Mn, ^{45, 46, 47}Fe and ⁴⁹Ni, half-lives and decay spectra have been measured. In a few cases, γ coincidence measurements helped to successfully identify the initial and final states of transitions. In these cases, partial decay scheme are proposed. For the most exotic isotopes, ³⁹Ti, ⁴²Cr, ⁴⁵Fe and ⁴⁹Ni, which are candidates for two-proton radioactivity from the ground state, no clear evidence of this process is seen in our spectra and we conclude rather on a delayed particle decay. Received: 26 July 2000 / Accepted: 20 December 2000     

The 46Ti(p, γ)47V, 50Cr(p, γ)51Mn, 58Ni(α, γ)62Zn and58Ni(α, p)61Cu cross sections

The ${}^{46}\text{Ti}\text{(}\text{p}\text{, γ)}{}^{47}\text{V}\text{,}{}^{50}\text{Cr}\text{(}\text{p}\text{, γ)}{}^{51}\text{Mn}\text{,}{}^{58}\text{Ni}\text{(α,γ)}{}^{62}\text{Zn and}{}^{58}\text{Ni}\text{(α, p)}{}^{61}\text{Cu}$ cross sections have been measured in the energy range of interest for stellar nucleosynthesis during oxygen and silicon burning. The results are compared with statistical theory calculations which attempt to treat excited state effects and the γ-ray channel more realistically than previous calculations.     

58Ni: an unpaired band crossing at new heights of angular momentum for rotating nuclei

High-spin states in 58Ni have been investigated by means of the fusion-evaporation reaction 28Si(32S, 2p)58Ni at 130 MeV beam energy. Discrete-energy levels are observed in 58Ni at record-breaking 42 MeV excitation energy and angular momenta in excess of 30h. The states form regular rotational bands with unprecedented high rotational frequencies. A comparison with configuration dependent cranked Nilsson-Strutinsky calculations reveals an exceptional two-band crossing scenario, the interaction strength of which is strongly shape dependent.